1. Field of the Invention
The present invention relates generally to apparatus and methods for use in transtracheal oxygen therapy. More particularly, the present invention provides for a novel connector hub assembly which allows oxygen to be supplied through a micro-tracheal catheter while simultaneously introducing another material with the oxygen into the lungs of a patient.
2. The Background of the Invention
Patients suffering from chronic oxygen-dependent respiratory failure must have an almost constant supply of oxygen. Today, many patients with chronic oxygen-dependent respiratory failure use nasal cannulas as part of their oxygen therapy. With nasal cannula therapy, patients receive needed oxygen through tubes which extend from the oxygen supply into the nasal passages and are attached with a harness at the ears and nasal septum.
There are some disadvantages associated with nasal cannula therapy One disadvantage is that before the oxygen can reach the lungs, it must first pass through the nasal passages, the back of the mouth, and the vocal chords. When administered through this route, much oxygen escapes from the mouth and the nose and is wasted. Three problems result from this loss of oxygen. One is that the oxygen saturation level of the patient is lower than it would otherwise be if the oxygen had not been wasted. This makes it more difficult for the patient to exercise, and exercise is often an important component of recovery for such patients. A second problem is that since much of the oxygen is wasted, patients are forced to carry with them larger containers of oxygen than would otherwise be necessary. For many, this is not only burdensome, but immobilizing, particularly in the case of persons who may be seriously physically weakened due to age or illness. A third problem is the financial burden placed upon patients to purchase oxygen supplies that are depleted by inefficient delivery.
An additional problem with the use of typical nasal cannula devices is discomfort. A constant flow of dry, cold oxygen in the nasal passages causes drying of delicate nasal membranes. This drying can cause the nasal passage tissues to swell and become irritated. As a consequence, less oxygen is delivered through the swollen nasal passages making breathing more difficult so that frequently, a patient will attempt to breathe through the mouth, which further complicates the drying problem. This problem is especially acute during the night when oxygen saturation levels are already at their lowest.
In addition, because the nasal cannula is attached around the ears of the user, the harness often irritates the tops of the ears. Because of these side-effects of nasal cannula therapy, patients have been reluctant to continuously wear such nasal cannula devices as prescribed. Thus, the effectiveness of the therapy is reduced.
In addition to the inefficient use of oxygen with nasal cannula, the need to draw oxygen through the nasopharyngeal and laryngotracheal dead space contributes to dyspnea and leads to recruitment of the accessory muscles of respiration. The use of these muscles requires exertion which in turn increases the need for oxygen.
Devices and methods have been developed which solve many of these problems. One such method, called transtracheal oxygen delivery, uses a micro-tracheal catheter inserted into the trachea through the skin at the base of the throat. On the end of the catheter is attached a luer connector which couples the catheter through an oxygen supply tube to an oxygen source. With the use of this device, oxygen is neither lost nor wasted because it is delivered into the trachea directly above the lungs. Thus, oxygen delivery is more efficient. This efficiency allows patients to be more mobile because they may carry around smaller containers of oxygen. Another advantage is better oxygen saturation as a result of delivery closer to the lungs.
To overcome many of the disadvantages of other methods, micro-tracheal catheters were developed to have as little impact on a patient's lifestyle as possible. The catheter was developed to be as small as possible and still be capable of delivering the necessary one to six (1-6) liters per minute flow required by most adult patients. The supply tube from the oxygen supply may be concealed under the patient's clothing and the supply itself is often contained in an easy-to-carry and discrete container. Even the puncture and installation procedure itself takes little more than fifteen minutes and recovery is usually swift.
After local and topical anesthesia is administered, a puncture is made and the micro-tracheal catheter is inserted into the trachea between two of its upper cartilaginous rings. Insertion is usually accomplished with an internal needle or needle, guidewire, dilator technique.
The microtracheal catheter is slid over the guidewire into the bronchial tree. The guidewire reduces trauma and the risk of kinking.
At this point, the catheter is completely advanced into the trachea until the retention strap abuts the skin and the catheter is no longer visible. With the guidewire serving as a roentgenologic marker, chest radiographs can be performed to document the positioning of the catheter. The guidewire is then removed and the retention strap is sutured to the neck and secured around the patient's neck to retain the catheter in place. Oxygen is later attached and the previous method of oxygen delivery removed.
The benefits of the micro-tracheal catheter often include the restoration of smell and taste and occasionally libido. The appliance has little cosmetic intrusion and mobility is higher than with any other form of treatment. As a result of these benefits, patients often resume pretreatment activities and generally achieve a higher standard of life.
This device and method also solve the problem of irritation of the nose and face. Since the oxygen does not have to pass through the nose, the nasal tissues do not become dry and irritated. Further, there are no facial attachments to irritate or encumber the face and ears.
A further advantage of the micro-tracheal catheter and method is the fact that it assists the patient in breathing. Breathing requires a certain amount of work. If a patient has chronic obstructive lung disease, the amount of work needed to breathe is increased. This work is reduced by the delivery of oxygen directly to the lungs under the pressure of an oxygen tank. Thus, with transtracheal oxygen delivery a patient is able to work less to get the same volume of oxygen to the lungs.
The size of the micro-tracheal catheter requires a much smaller opening (0.2 to 0.3 cm long) than that required for transtracheal tubes formerly used and is, therefore, more cosmetically appealing than either nasal cannula or larger tracheal tubes.
As illustrated in FIG. 1, when a transtracheal catheter is placed in the trachea, it must be able to make an abrupt bend after the catheter passes through the neck of the patient so as to extend the distal end of the catheter down toward the lungs. This bend serves to assist in locating the microtracheal catheter at the back of the trachea and away from the more sensitive sides. Since transtracheal catheters are directly connected to the oxygen supply tube through the luer connector, or to the neck through sutures, no rotation of the oxygen supply tube in relation to the neck is allowed. If the catheter is not flexible enough and does not have sufficient circular memory and resiliency, certain kinds of abrupt action such as swallowing, turning the head, coughing and the like will tend to result in kinking, and possibly irritation to the sides of the trachea.
Another problem associated with transtracheal catheters arises from the direct introduction of oxygen into the trachea. Such introduction bypasses the natural moisturizing action of the upper respiratory tract. Oxygen dries the trachea and lungs and so, requires regular irrigation with saline solution. Irrigation loosens secretions, stimulates expectoration, and moisturizes the lungs.
With existing systems, irrigation is accomplished by disconnecting the patient from oxygen and instilling saline solution into the transtracheal catheter of the patient. Droplets of the saline solution then contact the carina, and that cough center is stimulated to violent coughing. While this coughing action helps to clear the bronchial pathways, loosens secretions and cleanses the respiratory tract, coughing involves the expenditure of work and therefore, is an oxygen consumptive activity. The period when a patient requires the most oxygen is exactly at the time that the oxygen is disconnected. This situation often results in hypoxia during instillation. Since instillation is required from two to four times daily, it is easy to see why patient compliance has historically been low.
Another problem associated with the droplet nature of the solution being introduced is its inability to penetrate into the lungs for any distance. The droplets remain consolidated and are carried back up in the violent coughing that accompanies their presence near the carina.
A new problem associated with the small size of the micro-tracheal catheter occurs during irrigation. As the oxygen pressure is disconnected and saline solution introduced, the mucous dislodged by the violent coughing often fouls the tip of the micro-tracheal catheter pluging the opening thereof. This plugging may require the extraction of the catheter for cleaning or an additional irrigation procedure. Extraction necessitates the discontinuation of oxygen delivery. Other means must be used, such as nasal cannula or masks, if the patient must endure without oxygen for period while the catheter is cleaned. In some early micro-tracheal catheters this operation was required several times a day. While more modern catheters are constructed of materials to resist mucous build-up and clogging, violent coughing continues to occasionally plug the micro-tracheal catheter tip when no oxygen flow is present.
Another problem arising from the small size of the micro-tracheal catheter is illustrated in FIG. 1. The relatively heavy oxygen supply line, because of its connection to the micro-tracheal catheter some distance from the throat, tends to move the catheter about the trachea. This movement causes irritation or tickling of the trachea and may eventually wear on the sensitive sides of the trachea as the catheter is jostled from its usual position resting on the rear of the trachea. This movement causes coughing and discomfort and may eventually create irritation to the sides of the trachea.
Many physicians take advantage of the ability of the micro-tracheal catheter to inject medication directly into the lungs. This process, will also require the discontinuation of oxygen to the patient with the same resultant lapse in oxygen delivery. The medication is injected into the micro-tracheal catheter with a syringe or other device and enters the lungs in droplet form. While this introduction method is preferred over oral introduction, penetration into the lungs is still limited by the droplet form of the medication.